Dear RL,Welcome to the Spasmodic Dysphonia Bulletin Board. There are alot of voice patients who read and post here who are knowledgable about (and have lived with) our disorder, as well as the "family" of disorders SD belongs to. Neurological Movement Disorders, of which "Dystonia" is one. SD is a dystonia.
SD is a "focal" dystonia (focused in one body part - normally "adult onset"). It is virtually unknown (at least in acknowledged studies) for multiple family members to have SD.
Two suggestions/thoughts which may apply to your case:
"Dystonia-research" which demonstrates that a gene is transmitted (in the families with DYT1 genes which result in Generalized Dystonia - "early onset") still reveals that only about 30% of the positive genes actually result in clear dystonia cases.
IF (and I emphasize "IF") a gene is ever identified for SD, it "probably" would not result in children getting it, based on current genetic research, and statistics. The DYT1 research is an excellent example of Dystonia patients, with a clear genetic connection, NOT getting dystonia.
SD will likely continue to be extremely rare.
The most important thing is, based on your post (regarding your boyfriend's family including three SD patients?), I hope his relatives will apply to the NIH (National Institutes for Health in Bethesda, MD) for a study. There are currently such Family-Studies taking place. I'm only aware of one family with three cases, and only two members of that family are still living. The NIH is willing to conduct studies of such families, by taking blood samples. Multiple members of a family with SD is extremely rare.
The information you mentioned in this post could be important for future research on SD. Regarding reproducing, I wouldn't worry about it. There is no direct connection, through the generations, for SD. Neurological connections, possibly? But, not SD, per se.
Also, as you indicate, if you and your boyfriend are not sure what his relatives have, it might be good to encourage them to get diagnosed. They may have something else. If they have vocal tremors; however, there could still be a neurological connection.
Good luck, and keep in touch with us on this. This is quite interesting. Where are you located?
--Lynne (AD-SD; Northern California)
